Origins of Intelligence Testing

Intelligence Test a method of

assessing an individual’s mental aptitudes and comparing them to those of others, using numerical scores

Origins of Intelligence Testing

Mental Age a measure of intelligence test

performance devised by Binet chronological age that most

typically corresponds to a given level of performance

child who does as well as the average 8-year-old is said to have a mental age of 8

Origins of Intelligence Testing

Stanford-Binet the widely used American

revision of Binet’s original intelligence test revised by Terman at

Stanford University

Origins of Intelligence Testing

Intelligence Quotient (IQ) defined originally the ratio of

mental age (ma) to chronological age (ca) multiplied by 100 IQ = ma/ca x 100)

on contemporary tests, the average performance for a given age is assigned a score of 100

Brain Function and Intelligence

People who can perceive the stimulus very quickly tend to score somewhat higher on intelligence tests Stimulus Mask

Question: Long side on left or right?

Assessing Intelligence

Aptitude Test a test designed to predict a

person’s future performance aptitude is the capacity to learn

Achievement Test a test designed to assess what a

person has learned

Assessing Intelligence

Assessing Intelligence

Wechsler Adult Intelligence Scale (WAIS) most widely used intelligence test subtests

verbal performance (nonverbal)

Assessing Intelligence: Sample Items from the WAIS

VERBAL

General Information Similarities Arithmetic ReasoningVocabularyComprehensionDigit Span

PERFORMANCE

Picture Completion Picture ArrangementBlock DesignObject AssemblyDigit-Symbol Substitution

Assessing Intelligence

Standardization defining meaningful scores by comparison

with the performance of a pretested “standardization group”

Normal Curve the symmetrical bell-shaped curve that

describes the distribution of many physical and psychological attributes

most scores fall near the average, and fewer and fewer scores lie near the extremes

The Normal Curve

Assessing Intelligence

Reliability the extent to which a test yields

consistent results assessed by consistency of scores on:

two halves of the test alternate forms of the test retesting

Validity the extent to which a test measures or

predicts what it is supposed to

Assessing Intelligence

Content Validity the extent to which a test samples

the behavior that is of interest driving test that samples driving tasks

Criterion behavior (such as college grades)

that a test (such as the SAT) is designed to predict

the measure used in defining whether the test has predictive validity

Assessing Intelligence

Predictive Validity success with which a test predicts

the behavior it is designed to predict

assessed by computing the correlation between test scores and the criterion behavior

also called criterion-related validity

Assessing Intelligence

As the range of data under consideration narrows, its predictive power diminishes

Greater correlationover broad rangeof body weights

10

9

8

7

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5

4

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2

1

0

Little corre-lation withinrestricted

range

Football linemen’s

success

Body weight in pounds180 250 290

The Dynamics of Intelligence

Mental Retardation a condition of limited mental ability indicated by an intelligence score below

70 produces difficulty in adapting to the

demands of life varies from mild to profound

The Dynamics of Intelligence

Genetic Influences

The most genetically similar people have the most similar scores

Genetic Influences

Heritability the proportion of variation among

individuals that we can attribute to genes

variability depends on range of populations and environments studied

Genetic Influences

Group Differences

Group differences and environmental impact

Variation within group

Variation within group

Difference within group

Poor soil Fertile soil

Seeds

Group Differences

The Mental Rotation Test

Which two of the other circles contain a configuration of blocksidentical to the one in the circle at the left?

Standard Responses

Group Differences

Stereotype ThreatA self-confirming concern that one will be evaluated based on a negative stereotype